Mott Insulator-Superfluid Transition in a Generalized Bose-Hubbard Model with Topologically Non-trivial Flat-Band

TL;DR

This paper investigates the phase transition between Mott insulator and superfluid in a generalized Bose-Hubbard model on a checkerboard lattice with topologically nontrivial flat bands, revealing flat-band quasi-particles in strong interactions.

Contribution

It introduces a mean-field approach to analyze the phase diagram and flat-band properties in a topologically nontrivial lattice Bose-Hubbard model.

Findings

Phase diagram of the model obtained via Landau theory

Energy gap and dispersion of quasi-particles calculated

Flat bands observed in quasi-particle and quasi-hole spectra in strong interactions

Abstract

In this paper, we studied a generalized Bose-Hubbard model on a checkerboard lattice with topologically nontrivial flat-band. We used mean-field method to decouple the model Hamiltonian and obtained phase diagram by Landau theory of second-order phase transition. We further calculate the energy gap and the dispersion of quasi-particle or quasi-hole in Mott insulator state and found that in strong interaction limit the quasi-particles or the quasi-holes also have flat bands.